精细PBL模式及其诊断应用

AN IMPROVED PBL MODEL AND ITS DIAGNOSTIC APPLICATION

关键词:  非静力  E-ε湍流闭合  复杂地形  PBL数值模拟

Key words:  nonhydrostatic model  energy closure (E-ε)scheme  complex terrain  PBL numerical simulation

摘要:

在已建立的一种三维非静力细网格E-ε湍能闭合的动力学框架基础上,作了一些改进的技术处理和试验,包括:(1)利用GIS提供的地形资料,较精确地计算太阳辐射,进而诊断地面温度;(2)引进位势流概念,处理稳定层结条件下初始内插风场的风向变化;(3)引入动力学调整项G(α_obs-α).在此基础上,就地理信息系统(GIS)提供的一个 60km×48km区域作了边界层结构和湍流特征的数值模拟试验,并与实测作了比较,讨论了精细PBL模式的模拟效果,结果表明,新建的PBL模式能较好地模拟表征出复杂下垫面地域的陡峭地形和不规则海岸线对局地风场和湍流场的动力和热力学作用。

Abstract:

Based on a 3-dimensional fine-mesh non-hydrostatic and energy closure (E-ε)scheme, the present study makes some modification and numerical tests, as follows: (1) making use of the terrain data from GIS (geography information system), the distribution of solar radiation is calculated more precisely, so that the surface temperature is diagnosed more exactly. (2) potential flow concept is introduced to the interpolation of l/r² scheme, for consideration of wind deflection under the stable stratification condition. (3) A dynamical adjustment term, G(α_obs-α), is applied. Numerical tests are made for the Hong Kong area (60km×48km) and PBL simulation are obtained with the data provided by GIS. It is shown that the improved PBL model can simulate more reasonably the effect of the abrupt terrain and irregular coasts. effects on local wind fields and turbulence field over complex terrain. It is also shown that the results obtained from this model better agree with observations.